Monitoring Water Bugs (Macroinvertebrates)
Macroinvertebrates are animals that don't have a backbone and are visible to the naked eye. They are very useful in telling us how healthy or unhealthy a waterway is. Some water bugs are very sensitive to pollution, so will not be found in a polluted waterway. Checking to see which water bugs are in the waterway and which are not can tell us how healthy the waterway is. Sites with good quality water have many different kinds of water bugs.
There are many different types of water bugs. To survive, each type has specific environmental requirements. Changes in water quality can lower the numbers of some water bugs and increase numbers of bugs which are more tolerant to changed conditions or pollution. Bugs that can survive polluted conditions usually increase in number because there is less competition and predation from other macroinvertebrates.
Sensitivity Levels of Water Bugs
| Very Sensitive | Animals are only likely to be found in streams with good water quality |
|---|---|
| Sensitive | Animals are usually only found in streams with good or medium water quality |
| Tolerant | Animals can be found across a range of water quality in streams, but can live in poor-quality water |
| Very Tolerant | Animals can be found in water or poor to good quality, but are usually the most abundant group in streams with poor water quality |
A water bug sample scores the different types of bugs according to their sensitivity, as well as the abundance of the bugs. This is then plotted on the Stream Condition Chart which tells us the condition of the stream.
